19-Nordeoxycorticosterone (19-norDOC) is a powerful mineralocorticoid that has been postulated to play a role in the pathogenesis of some forms of hypertension in the rat. We measured the daily excretion of 19-norDOC, aldosterone, and corticosterone in intact male and female SR/jr rats for 20 consecutive days. The excretion of corticosterone and aldosterone was higher during the first 4 days of collection and remained relatively stable for the rest of the collection period. The excretion of corticosterone and aldosterone was not different between male and female rats. The excretion of 19-norDOC, which, as has been reported previously, was significantly higher in female than male rats, varied over 600% from day to day in some individual rats. The variability in the excretion of 19-norDOC did not correlate with the excretion of aldosterone or corticosterone and did not appear to coincide with an estrous cycle. These studies also indicate that when the urinary excretion of steroids is intended to be used as an indication of steroid production in the basal state, a period of at least 4 days of acclimatization in metabolic cages, even for animals accustomed to handling, is necessary to obtain stable excretions.